Ruili, a border city in Yunnan province, reported eight new confirmed locally transmitted COVID-19 cases on Thursday — all found through citywide nucleic acid testing, local authorities said.

Three of the cases were Myanmar nationals and five were Chinese. All were sent to a designated hospital for treatment. None of the patients is in serious condition.

The Wanding area of Ruili asked all residents to remain quarantined at home starting at 2 pm on Thursday. All schools and training institutions suspended classes, and places of business, except for some supermarkets, hospitals and pharmacies, were closed. Restaurants may provide take-out service only.

Workers involved in epidemic control, medical services or city operations, as well as security guards or people involved in the delivery of necessities, are allowed to travel within the area with a pass, according to a notice from Wanding's epidemic prevention and control headquarters.

The headquarters also organizes workers to deliver daily necessities to residents. Any resident with an emergency or sudden illness can call 110, 120 or 119 and report to their community workers, it said, adding that it will strengthen efforts to crack down on people-smuggling.

Shang Labian, the mayor of Ruili, told China Central Television in an interview on Wednesday, that the border in Ruili has no natural barriers, and 68 percent of its population live next to the line, which poses challenges for epidemic control.

Ruili's Jiegao community — which was hit hardest by the virus in the most recent outbreak — borders Myanmar on three sides. Many foreigners live or do business there, he said, and have done since the 1980s. He added that many people were stranded in Jiegao after the outbreak in September. About one-third of Jiegao's 15,000 people are foreigners.

As of Thursday, Yunnan province had reported 31 confirmed locally transmitted COVID-19 cases, 78 imported confirmed cases and 17 imported asymptomatic carriers. All are getting treatment or are being observed.